California Gold Rush: (1848 ? 1855) A mass migration of people moving to California in search of gold after it was discovered by James W. Marshall at Sutter's Mill in Coloma, California, on January 24, 1848. The news of gold brought some 300,000 people to California from the rest of the United States and abroad. Californios: A Spanish term for "Californian" that was used to identify a Spanish-speaking, mostly Roman Catholic people who were born in Alta California. People identified as Californios were born in the period starting with the first Spanish colonies established by the Portol? expedition in 1769 and ending with the Treaty of Guadalupe Hidalgo in 1848, when Mexico ceded Alta California to the United States. Chinese Exclusion Act: